Question about 1999 Chevrolet Silverado 1500

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1998 Chevy Truck 1/2 ton 350 engine. Trouble codes P0404, P0405 and P1404. I replaced the EGR valve. Now I get t/c P0404 and P0405. Now what should I check?

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  • David Sharp May 11, 2010

    Did you clean the port holes and checked for vaccum and exhaust pipe was working when it was off?



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  • Chevrolet Master
  • 2,007 Answers

404 is exhaust gas recirculation circuit, and 405 is exhaust gas recirculation sensor circuit low. EGR sensor or ground?

Posted on Nov 13, 2009


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I have a 1997 olds achieva with codes p0404 and p0405. i have replaced the egr valve with no change in codes.

when codes are set it does not mean a part is defect ,there is wires connect to it. EGR solenoid are 3 solenoid with 3 holes one 1/7orifice: second is 2/7 third 4/7 pcm command those solenoid to obtain the right amount of exhaust but P0404 said performance is bad and P0405 said circuit A is low or 0volt . pull wire one by one see if it bounce mean wire is cut inside

Sep 14, 2013 | Oldsmobile Cars & Trucks

1 Answer

I am getting two codes from my 05 equinox it's

    EGR Sensor Circuit Range/Performance, Stuck Open, to fix, either clean out or replace it, this should do it. p1404 relates to same problem. replace EGR and you should be ok. dont forget to clear the code when repaired.

    May 01, 2012 | 2005 Chevrolet Equinox

    1 Answer

    I have a 2005 6.0 liter powerstroke f-350 with codes P0404 and P0405, I have tried cleaning the egr valve and reset the code worked fine for a little while then the codes came back.

    I have a 2005 6.0 liter powerstroke f-250 with P0404 and P0405, I have tried cleaning the egr valve and reset the code worked fine for a little while then the codes came back. Any Idea what's going on?

    Jun 15, 2010 | 2003 Ford F150 Regular Cab

    2 Answers

    1998 Chevy Tahoe with P0404, P0405, and P0430 Trouble Codes

    Check for

    vacuum leaks on intake manifold,

    the air tube between the air filter.

    intake manifold vacuum hose.

    clean throttle plate with Berryman carburator cleaner

    SEE sample picture HERE

    Also remove carbon built up behind the EGR valve and the EGR passage tube.


    Vacuum leak WILL offset the intended 14.7 to 1 air fuel ratio.

    More un-metered air (leaks) will lean out the fuel mixture.

    Use small amount of Berryman carb clearer at potential air leak area will help you identify trouble spot.

    At idle,just spray and listen for the RPM surge.

    The in-rush of carb clearer will increase the RPM on the motor.

    Record the problem spot(s) and address it later.


    EGR carbon built up require 2+ hours to clean from start to finish.

    You will need a new EGR base gasket before your start.

    Locate and remove the EGR valve after the vehicle is cool down.

    Carefully record the connector and vacuum line (for older vehicle) location by drawing an easily to follow diagram.

    Remove the EGR valve.

    Inspect the location of the carbon built-up inside the valve and the EGR passage tube.

    SOAK these areas with WD-40 spary.

    You will need a small screwdriver,cloth hanger and lot of newspaper and time to get this cleaning done right.

    RE-SOAK the carbon and let it sit for over-night will also help.

    One the last round,pass a shop vacuum of the EGR valve and the passage pipe.

    Install the new EGR gasket and connectors.

    Allow the vehicle to warm up outdoor to burn up any remaining WD-40.

    Take it for a test drive.

    Please rate my answer if it's useful to you.



    Sep 24, 2009 | 2000 Chevrolet Tahoe

    1 Answer


    Exhaust Gas Recirculation System Is the main problem here. the other code P0118 may be a bad temprature sensor or your thermostate needs to be changed. Last it could be a weak water pump. 

    So what is an EGR system and how does it work? EGR stands for Exhaust Gas Recirculation, and as its name implies, this system allows exhaust gasses from your car to be re-circulated into the engine, helping to reduce emissions. These systems are mostly comprised of the EGR valve, a DPFE (Delta Pressure Feedback EGR) sensor, hoses, a vacuum regulator, some vacuum lines, wiring, the computer and the exhaust tube leading to the valve itself. 
    The car's wiring can be tested in the normal fashion by looking for broken and lose wire, and all vacuum lines can be checked easily for cracks, leaks and correct routing.
    The last thing i would then check is the the EGR valve, EGR vacuum regulator and DPFE sensor (or similar flow sensor).
    I hope this helps and good luck

    Apr 09, 2009 | 1998 Pontiac Sunfire

    2 Answers

    I replaced my egr valve on my 2001 chevy venture 1 1/2 yrs ago,

    I found an answer that worked for me here. (I have a 2001 Chevy Venture.) case links are not allowed, here's the text:That code is the EGR. I'd start by checking for a bad connection on the EGR plug-in. Pull the connector off and inspect each individual terminal inside the plug and the connector pins inside the EGR valve.
    I found this solution at another forum on this issue. It worked on my 2001 Grand Am:

    "Many GM built cars have a tendency to have the 'Check Engine Soon' light come on as a result of DTC code P1404. P1404 is described as EGR valve pintle stuck open, which in most cases is a false alarm. I had this happen with my '01 Grand Am. A little bit surfing on internet reveals that GM has a solution for the problem, a re-flash for the car's computer.

    A software re-flash as a fix kind of indicates that the vehicles with this problem were built with it but I don't think GM will be re-flashing cars outside warranty for free. They will want their $100 for it.

    Some hands on people I found had purchased a new EGR valve and changed it but the problem remained.

    Possible reason (very likely) for the false P1404 code is that the plastic piston of the EGR valve position instrument (LVDT?) wears over time and starts reading a different position at valve closed than what it was when the EGR valve was first installed.

    When the car was built and the computer circuits energized for the first time the computer learned the EGR valve closed position signal from the valve position instrument that is built on top of the valve itself. Over time, when the instrument wears, a slightly different signal is sent to the computer and when it differs enough from the 'Valve Closed Signal', that the computer had learned, the trouble code P1404 is set and the 'Service Engine Soon' light comes on.

    Replacing the EGR valve with a new one does not necessarily fix this problem because the 'Valve Closed Signal' between valves is slightly different and it is just pure luck if your new valve would give a 'Valve Closed Signal' close enough to your original valve's signal not to set the trouble code. This is why the new EGR valve 'Valve Closed Signal' must be re-learned by the computer.

    So, what this all means is that if the P1404 is a false code meaning that the valve pintle is not stuck open, then new 'Valve Closed Signal' can be re-learned by the computer using the old valve.

    For fixing this problem the tool you need to have is a simple OBD II code scanner that can be used to erase trouble codes. There are many scanners of different price range on the market. I purchased one from AutoZone for about $90.

    A code scanner is a very handy tool to have and I recommend everybody who is just slightly hands on type of a person to get one. It will end up saving a lot of money over time.

    The fix goes like this:

    1. Disconnect the wire harness from the EGR valve.


    3. Re-connect EGR wire harness and your problem should be fixed.

    Mar 27, 2009 | 2001 Chevrolet Venture

    1 Answer

    Disgnostic code meaning

    P0404 Exhaust Gas Recirculation Control Circuit Range/Performance
    P0405 Exhaust Gas Recirculation Sensor “A” Circuit Low

    It sounds like you have a failure of the EGR valve.

    Sep 28, 2008 | 2000 Chevrolet Tahoe

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